1. Field of Invention
The present invention relates to physiological measurement techniques and biotelemetry (i.e., medical telemetry), and more particularly to a system, device, and method for heart and lung monitoring using a modulated radio frequency (RF) carrier, such as an IEEE 802.11(x) (“WiFi”) orthogonal frequency-division multiplexing (OFDM) signal, as a diagnostic signal.
2. Description of Related Art
Several technologies have been developed to help doctors and medical professionals access, visualize, or learn more about a patient's internal organs without having to undertake an invasive medical procedure.
For example, an electrocardiogram (an “EKG”) can be used to determine information about a patient's heart. Electrical waves generated by the heart are measured by electrodes that are placed on the skin of a patient. The voltage between the electrodes is displayed on a monitor for analysis of the patient's heart. EKGs have several disadvantages, however. The electrodes must be physically connected to the patient being monitored, which can be bothersome to the patient, for the duration of the EKG test. In addition, an EKG does not produce an image of the heart itself and is not a direct measurement of the motion of the heart. Therefore, the detected electrical characteristics are merely analogues of the heart's motion.
Computer axial tomography (“CAT” or “CT”) scans can be used to generate three-dimensional (3D) images of a human body. CT scanners emit a fan-shaped x-ray beam, which passes through a patient's body before being detected by rotating source detectors. Depending on the type of tissue the x-rays pass through, the x-rays will be attenuated or will pass through unimpeded. The x-rays that pass through the body are detected and used to generate an image of the tissues exposed to the x-rays. Images of internal organs can therefore be generated. Yet, CT scanners suffer from numerous disadvantages. They are expensive, bulky and immobile, require patients to remain generally immobile for extended periods of time during the scanning, and expose patients to potentially harmful x-rays.
Magnetic resonance imaging (“MRI”) scanners can be used to generate images of a human body. An MRI scanner uses magnetic fields to align the nuclear magnetization of hydrogen atoms in the body. The magnetization of these atoms is then altered to produce a magnetic field, which is detected by the scanner and used to generate an image. As with CT scanners, MRI scanners are expensive, very large and immobile, and require patients to remain relatively immobile during the procedure. Furthermore, MRI scanners cannot be used by some people with metal implants.